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How to evacuate the cold storage refrigeration system?
Apr 11, 2018

   Cold storage refrigeration system evacuation is an indispensable process during installment and maintenance. Evacuation as it means, use vacuum pump and linkage with refrigeration system pipework, remove nonondensable gas and moisture, which can increase the refrigeration of whole system and decrease the downtime rate during usage of cold storage.


     function of evacuation to cold storage

⒈  Remove the non-condensable gas in refrigeration system, avoid non-condensable gas effect to make the system pressure higher.  Exhaust temperature is higher, which will affect the refrigeration of whole system, and carbonization of lubricant oil and badly affect the normal usage of compressor and cause problems to compressors.

⒉  Evacuate the moisture in the system can prevent acidification of lubricant oil action with moisture and lead to the rotting of system pipework and badly influence the compressor functioning. The moisture inside the pipe will blockade the system and badly affect refrigeration effect.

Evacuation should be done after system cleansing, dirt cleaning and leakage test. So it can further test the air tightness of the refrigeration system and remove the gas and moisture in the system and prepare well for refrigerant charging.

Evacuation should be done by vacuum pump. Use medium and small size opening type, semi-hermetic small size refrigeration system can utilize the system itself compressor without using vacuum pump, unless not allowed as per manufacturer instruction.一、 operation procedures using vacuum pump to evacuate

    1)Shut down valves of the system linking outside (e.g. filling valve, air releasing valve etc..) open all valves linking inside the system.

    2)Unfasten  exhaust valve side hole screw, open the side hole and connect with vacuum pump.

    3)start the vacuum pump to evacuate, the air is difficult to move one time for all, so it should be done several times with each interval of 10 min and make the system pressure balanced. The ammonia remaining pressure shall be less than 7.999kPa(60mmHg); Freon system remaining pressure shall be less than 1.333kPa(10mmHg)

    4)When it reach the vacuum state, firstly close the side hole, then stop vacuum pump, dissemble the air suction pipe, fasten the exhaust valve side hole screw.

    5)After 24 hours of evacuation, the system inside pressure shall not exceed 666.61Pa(5mmHg), otherwise should make sure the reason and solve the problem.


1) When the vacuum reaches 8.659kP, cannot proceed any other as the oil pressure of compressor is rather low.

2)during the use of compressor itself to make vacuum, if compressor has lubricant oil pump. As vacuum formed the working conditions of lubricant pump, it will cause damage to the machinery moving parts. So if the oil pressure is less than 26.7kPa, stop the machine immediately

3)After vacuum evacuation, it need cleansing of compressor, replace with new lubricant oil.


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